Medical Edge Newspaper Column

Treating Brain Aneurysms

September 23, 2007
Dear Mayo Clinic:
My granddaughter (age 30) has been diagnosed with a brain aneurysm. Can't an aneurysm be removed? So far they are just watching it and treating the headache. Wouldn't it be better to operate before it becomes an emergency? — Lake City, Minn.

Answer:
A brain aneurysm is a balloon or sac that forms on an artery that provides blood to your brain. They're actually quite common. Approximately 2 percent of the population, about 6 million people in the United States, have or will have a brain aneurysm. Cigarette smoking and high blood pressure increase the risk of forming an aneurysm.

Most brain aneurysms are small and don't ever cause symptoms. Many are detected on computerized tomography (CT) or magnetic resonance imaging (MRI) head scans performed for an unrelated reason, such as headaches, dizziness or stroke. Occasionally, if an aneurysm is large, it can press on brain structures and cause symptoms such as pain, numbness or vision changes. About 50 percent of aneurysms are detected after they burst (rupture), which causes bleeding around the lining of the brain. This is a type of stroke called a subarachnoid hemorrhage. Fortunately, it is uncommon, occurring in about 1 in 10,000 people per year.

When aneurysms are detected before they burst, the key question is whether they carry a significant risk of rupture. For many small aneurysms, that risk often is low, so they don't require treatment. There are exceptions, however. Aneurysm size, location and other features are all considered in determining the risk of rupture.

If an aneurysm requires treatment, two options are available. The first is a procedure called aneurysm clipping, in which a neurosurgeon performs brain surgery and places a tiny metal clip across the base of the aneurysm. The second is aneurysm coiling. In this procedure, an interventional neuroradiologist or neurosurgeon puts a small plastic tube (catheter) into a groin artery and advances it into the brain aneurysm. Tiny platinum coils are placed in the aneurysm until they fill the sac. The coils slow blood flow and promote the formation of blood clots, which help seal off the aneurysm. Both procedures can effectively treat a brain aneurysm. They aren't risk-free, however. The risk of the procedure needs to be balanced against the risk of leaving the aneurysm alone.

A person with a brain aneurysm should be evaluated by doctors — a neurologist, a neurosurgeon, and possibly a neuroradiologist — who can offer a careful assessment of the risks of not treating the aneurysm compared to the risks of treating it. Based on that evaluation, they may recommend that an aneurysm be left alone or be treated with surgery or coiling. For aneurysms that are not treated, repeat scanning with a special type of brain scan called magnetic resonance angiography (MRA) or computed tomography angiography (CTA) typically is performed six to 12 months after the aneurysm is detected. Scans may be performed again periodically in the future, to monitor for growth or other changes.

— Robert Brown Jr., M.D., Neurology, Mayo Clinic, Rochester, Minn.